Cameron, R. P., Speirits, F. C. , Gilson, C. R. , Allen, L. and Barnett, S. M. (2015) The azimuthal component of Poynting's vector and the angular momentum of light. Journal of Optics, 17(12), 125610. (doi: 10.1088/2040-8978/17/12/125610)
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Abstract
The usual description in basic electromagnetic theory of the linear and angular momenta of light is centred upon the identification of Poynting's vector as the linear momentum density and its cross product with position, or azimuthal component, as the angular momentum density. This seemingly reasonable approach brings with it peculiarities, however, in particular with regards to the separation of angular momentum into orbital and spin contributions, which has sometimes been regarded as contrived. In the present paper, we observe that densities are not unique, which leads us to ask whether the usual description is, in fact, the most natural choice. To answer this, we adopt a fundamental rather than heuristic approach by first identifying appropriate symmetries of Maxwell's equations and subsequently applying Noether's theorem to obtain associated conservation laws. We do not arrive at the usual description. Rather, an equally acceptable one in which the relationship between linear and angular momenta is nevertheless more subtle and in which orbital and spin contributions emerge separately and with transparent forms.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Barnett, Professor Stephen and Gilson, Dr Claire and Speirits, Dr Fiona and Cameron, Dr Robert |
Authors: | Cameron, R. P., Speirits, F. C., Gilson, C. R., Allen, L., and Barnett, S. M. |
College/School: | College of Science and Engineering > School of Mathematics and Statistics > Mathematics College of Science and Engineering > School of Physics and Astronomy |
Journal Name: | Journal of Optics |
Publisher: | Institute of Physics Publishing Ltd. |
ISSN: | 2040-8978 |
ISSN (Online): | 2040-8986 |
Copyright Holders: | Copyright © 2015 IOP Publishing Ltd |
First Published: | First published in Journal of Optics 17(12):125610 |
Publisher Policy: | Reproduced under a Creative Commons License |
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